Although prosthetic heart valves have been in clinical use since 1960, a need exists for a valve which does not require anticoagulants and has a long life expectancy. Coratomic has developed a valve which promises to meet his criteria. It resembles the human aortic valve, or the porcine or bovine valves, but is made of biocompatible, fatigue resistant Coraflex polyurethane. The valve is designed to have minimal membrane stress, shear stress, and subsequent hemolysis. The valve has been tested in a cardiac pulse duplicator and in dogs, demonstrating flow characteristics similar to porcine valves, which do not require anti-coagulants. In addition, to prevent valve calcification, the prosthesis will contain the anticalcification agent, ethanehydroxydiphosphonate (EHDP), in a slow release form (greater than 30 years extrapolated drug delivery) as both part of the leaflet structure and support ring. Phase 1 of the Research Program will consist of continued fatigue testing of the Coraflex valve on a specially designed heart valve fatigue test system. It provides dynamic pressure characteristics similar to those experienced in the actual operating environment. Phase I will also be concerned with in vito studies of EHDP controlled-released drug delivery from the prosthesis. Successful completion of fatigue testing and formulation of a suitable EHDP controlled-release drug delivery system in Phase 1 would lead to complete performance and animal tests in Phase 2, preparatory to clinical trials in Phase 3.